docs: def as_currency(self, currency='USD', locale=LOCALE_OBJ, *args, **kwargs):
          """Format subset as currency
  
          :param currency: Currency
          :param locale: Babel locale for currency formatting
          :param subset: Pandas subset
          """
          f = Formatter(
              as_currency(currency=currency, locale=locale),
              args,
              kwargs
          )
          return self._add_formatter(f)